Capture and Separation of SO₂ Traces in Metal–Organic Frameworks via Pre‐Synthetic Pore Environment Tailoring by Methyl Groups

Abstract

Herein, we report a pre-synthetic pore environment design strategy to achieve stable methyl-functionalized metal-organic frameworks (MOFs) for preferential SO₂ binding and thus enhanced low (partial) pressure SO₂ adsorption and SO₂ /CO₂ separation. The enhanced sorption performance is for the first time attributed to an optimal pore size by increasing methyl group densities at the benzenedicarboxylate linker in [Ni₂ (BDC-X)₂ DABCO] (BDC-X=mono-, di-, and tetramethyl-1,4-benzenedicarboxylate/terephthalate; DABCO=1,4-diazabicyclo[2,2,2]octane). Monte Carlo simulations and first-principles density functional theory (DFT) calculations demonstrate the key role of methyl groups within the pore surface on the preferential SO₂ affinity over the parent MOF. The SO₂ separation potential by methyl-functionalized MOFs has been validated by gas sorption isotherms, ideal adsorbed solution theory calculations, simulated and experimental breakthrough curves, and DFT calculations.